1. Field of the Invention
The present invention relates to a liquid crystal display device, in particular, a liquid crystal display device having a direct-type backlight structure.
2. Description of the Related Art
FIG. 13 is an exploded perspective view of a conventional typical liquid crystal display module which is used for a television, a picture receiver, or the like. The upper side of FIG. 13 is the display screen side, whereas the lower side corresponds to a back surface of a liquid crystal display device.
A liquid crystal display module 900 includes a liquid crystal display panel 920 sandwiched between a backlight assembly 930 and an integral-type or separate-type bezel 910. The liquid crystal display panel 920 is obtained by assembly performed in a different step. The liquid crystal display module 900 is supported and fixed at a predetermined position by fastening means. In some cases, the liquid crystal display panel 920 is supported through an intermediation of an elastic body (not shown) between the liquid crystal display panel 920 and any one of the backlight assembly 930 and the bezel 910.
The backlight assembly 930 is obtained by supporting and fixing a backlight member at a predetermined position by fastening means so that the backlight member is sandwiched between an integral-type or separate-type resin frame 931 and a base plate 937. The backlight member includes: a plurality of optical sheets 932; a plurality of supporting members 935 for the optical sheets 932; a plurality of cathode fluorescent tubes 934 corresponding to light-emitting means; cathode fluorescent tube end covers 933; and a reflecting sheet 936 corresponding to light-reflecting means. The cathode fluorescent tube end covers 933 are located on the right and left sides of the liquid crystal display panel 920 and are capable of supporting the cathode fluorescent tube 934 so as to sandwich the cathode fluorescent tube 934 therebetween. On a back surface of the base plate 937, a cathode fluorescent tube lighting circuit board 938, which is electrically connected to the cathode fluorescent tubes 934, is mounted. Contrary to the liquid crystal display device using the large number of cathode fluorescent tubes as described above, a display device having a reduced number of cathode fluorescent tubes for display is sought after in response to recent requests for electric power saving and lower cost.
JP 2007-149343 A discloses the following light-source device to solve a problem of uneven brightness. The light-source device has a reflecting plate in the form of dual half-ellipses for each of a plurality of linear light sources corresponding to light-emitting means. Specifically, the cross-sectional shape of the reflecting plate has partial contours of two ellipses, which share a common focal point present directly above the linear light source.
JP 2002-196326 A discloses a backlight device to solve a problem of lowered light-emission efficiency of a light source corresponding to light-emitting means due to heat generated by the light source itself. In the backlight device, each of a plurality of cold cathode fluorescent tubes corresponding to the light-emitting means is located at a focal point of a parabolic cross section of a reflecting plate corresponding to light-reflecting means.